Device for sawing plastic masses



Nov. 27, 1956 c. G. B. BERGLING DEVICE FOR SAWING PLASTIC MASSES Filed Nov. 15, 1954 DEVICE FOR SAWING PLASTIC MASSES Application November 15, 1954, Serial No. 468,905

3 Claims. (Cl. 125-18) When manufacturing building stone from, for instance light-weight concrete, the concrete mass is first poured into large slabs, which are allowed to set only partly, after which they are sawn into smaller slabs and then allowed to set further, until ready.

The present invention concerns a device for sawing plastic masses such as light-weight concrete, comprising at least one core-wire, suitably strapped into a frame, and around which wire spirals are arranged, and which wire spirals are arranged in at least two sections along the corewire and with alternating pitch in adjoining sections.

The invention will be further described in the following and with references to the enclosed drawing, where Fig. 1 shows a vertical section through a light-weight concrete slab and a sawing wire, which has partly cut through the light-weight concrete slab, and Fig. 2 shows in a larger scale, how the core-wire may be suspended, and how the outer wire may be fastened to and wound around the corewire.

The sawing wire consists of a core-wire 1, suitably comprising a high-quality steel-wire, the two end of which are fastened in collets 2 arranged to grip sockets 3, arranged on the wires. The sockets 3 are drilled through, and threaded on the wire, and fastened through upsetting or clamping. The holes in the sockets are sized according to the diameter of the core-wire, and they cannot be pulled oit the core-wire, after the same has been deformed in a proper manner.

The collets 2 are fastened to a frame 10, made from pipe. The collet fastened to one end of the sawing wire. is suitably spring suspended from above frame, by means of a helical spring 11. By this means, damage to the wires is prevented, if during the sawing they would meet some obstruction in the light-weight concrete mass. When sawing, a reciprocating motion is imparted to the frame 10 in the direction of the core-wires, thus obtaining an effective sawing action.

Around the core-wire an outer-wire 4 is arranged, which is wound around the core-Wire in such a way, that parts 6, with right-hand pitch will alternate with parts 7, with left-hand pitch. The parts 6 and 7 are preferably of the same length. In the most simple case, half of the sawing wire is wound with right-hand pitch, and the other half with left-hand pitch. Where the windings change their pitch, a loop or a knot 5 is made. The length of the States Patent 2,771,872 Patented Nov. 27, 1956 parts 6 and 7 may vary, but to mm. (abt. 4" to 6") has proven to be a suitable length. The corewire should be of larger diameter than the outer wire, and the best results, when considering the sawing, as well as the strength of wires, have been obtained, when the crosssection area of the outer wire has been about 20% of the area of the core-wire. The ends of the outer wires are fastened to the core-wire by means of winding the ends 17 around the core-wire and securing with a socket 16.

With the reciprocating motion of the sawing wire through the mass, 21 sawing performance is executed, which is made easier through the outer wire, which through its pitch, which hereby serves as saw teeth, cuts away the material. A core-wire, which is wound with only right-hand or only left-hand pitch cannot be used, because a core-wire s0 wound, would, while sawing, be pulled obliquely to one side. Through dividing the winding of the outer wire into a number of short parts, and having these alternate with right-hand and left-hand pitches, the pulling tendency of the windings counteract each other, and the cut will be absolutely straight. By plating the wires with tin or Zinc, the outer wire would be prevented from coming loose from the core-wire, and thus changing the pitch.

Fig. 1 shows a light-weight concrete slab 12 in the process of being sawn. The light-weight concrete slab is poured in a mold 13, the end walls 14 and 15 of which are lowered while sawing is going on. The mold is resting on a support 8, which continually rises during the sawing operation.

I claim:

1. A device for sawing plastic masses, such as lightweight concrete, comprising at least one straight corewire stretched between stretching means, and an outer wire having a smaller cross-sectional area being arranged in spiral form around said straight core-wire, the outer wire spiral being arranged in at least two sections arranged end-to-end along the core-wire with alternating pitch in adjoining sections, the outer wire between two adjoining sections being arranged to form a loop, which forms the turning point in the pitch directions of the two wire spirals.

2. A device as claimed in claim 1, in which the crosssectional area of the outer wire is about 20% of that of the core-wire.

3. A device as claimed in claim 1 wherein the ends of said outer wire terminate in advance of the terminal ends of core-wire.

References Cited in the file of this patent UNITED STATES PATENTS 1,662,488 Burkhardt Mar. 13, 1928 1,687,089 Green Oct. 9, 1928 2,451,383 DAvaucourt Oct. 12, 1948 2,633,681 Sam Apr. 7, 1953 FOREIGN PATENTS 447,300 Italy Apr. 6, 1949 574,574 France July 16, 1924 

